A passive optical network (PON) system is known as an example of an optical communication system. For the purpose of improving fault tolerance (also referred to as “availability”) of a PON system, optical transceiving modules of an active system and a standby system are sometimes provided in an optical line terminal (OLT).
[Patent Document 1] JP 2015-84470 A
When optical transceiving modules of an active system and a standby system are provided in an OLT, the OLT may become complex, the size thereof may increase, and the cost may increase.